How memories shape your reality | Aleena Garner | TEDxNewEngland

Key Concepts

• Internal Model: The brain's representation of the world, shaped by past experiences, present sensations, and future expectations.
• Memory Trace: A specific population of neurons activated during a unique experience, encoding that experience in the brain.
• Sensory Input: Information received through the senses (sight, hearing, smell, taste, touch).
• Perception: How we experience the world, resulting from the integration of sensory input and the brain's internal model.
• Expectation: What we predict will happen, influencing how we perceive current events.
• Associative Learning: Learning to associate certain stimuli (e.g., sounds and visual objects).
• Resilience: The ability to experience aversive events as less negative due to the presence of positive memories.
• Trauma/PTSD: Negative memories active during new experiences can make even positive events seem negative.

Sensation vs. Thought: The Basis of Perception

The video explores how our experience of the world is determined by both our senses (what we see, hear, feel, smell, and taste) and our thoughts (the brain's internal model). Dr. Garner emphasizes that every experience enters the brain through sensation but is then integrated with pre-existing thoughts and beliefs. This integration is crucial for how we perceive and interpret the world.

Memory Traces and Hybrid Memories

Dr. Garner's lab developed a method to tag and reactivate specific neurons (memory traces) associated with particular experiences in mice. They tagged neurons activated when mice explored a comfortable "mouse house." Then, they reactivated this memory trace while the mice were exploring a slightly aversive "doctor's office" environment. The result was the formation of a hybrid memory, where the positive memory of the house was fused with the negative experience of the doctor's office. This demonstrates that new learning is physically integrated into previous memory traces.

The Impact of Past Experiences on Present Perception

The experiment highlights that what we experience depends not only on the present sensations but also on past experiences. If a negative memory is active during a new experience, it can negatively color the perception of that new experience, even if it's inherently positive. This is relevant to understanding trauma and PTSD. Conversely, positive memories can buffer against negative experiences, contributing to resilience.

Expectations and the Internal Model

The video then shifts to the role of expectations in shaping perception. Dr. Garner explains that future experiences, or rather, our predictions about them, can change how we perceive the world now.

Virtual Reality Experiment: Associative Learning and Error Detection

To investigate how the brain integrates sensation with expectations, Dr. Garner's lab trained mice to play a video game in virtual reality. Mice learned to associate specific sounds (e.g., a 10.5 kHz tone) with specific visual objects (e.g., a triangle). Neural activity in the visual cortex was measured during this associative learning process.

Suppression and Amplification of Neural Activity

The results showed that the visual cortex processed the triangle differently depending on whether the mice expected to see it (after hearing the tone) or if it appeared unexpectedly. When the triangle was expected, there was a suppression of neural activity in the visual cortex. Conversely, when the triangle appeared unexpectedly, there was an amplification of neural activity. This suggests that the brain suppresses activity related to predicted stimuli and amplifies activity related to unexpected stimuli.

Updating Internal Models and Learning

The researchers then introduced errors into the virtual reality game, presenting the tone with the wrong visual object (e.g., a circle instead of a triangle). Some mice successfully updated their internal models and learned the new association (tone = circle). However, other mice failed to update their internal models and remained stuck expecting the triangle, demonstrating a failure to learn. This illustrates the importance of updating our internal models to adapt to a changing world.

Internal Models in Humans: MS-DOS vs. Windows 11

Dr. Garner uses the analogy of computer operating systems (MS-DOS vs. Windows 11) to illustrate the concept of internal models in humans. If we use an outdated internal model, we limit our experiences and fail to perceive the world accurately.

Actionable Insights: Changing Thoughts and Expectations

Dr. Garner concludes by offering actionable insights based on the research:

• Choose your memories: Intentionally trigger positive memories before engaging in challenging or unpleasant tasks.
• Be mindful of sensations: Distinguish between sensory input and pre-existing thoughts and expectations.
• Meditate and be deliberate with expectations: Become aware of unconscious expectations and consciously shape them.

Implications for Interpersonal Understanding and Education

The video emphasizes that everyone has a unique version of reality based on their individual experiences. This has important implications for interpersonal understanding and education. We need to acknowledge that others have different perspectives and adapt our communication and teaching methods accordingly. Everyone learns differently, but everyone is capable of learning.

The Superpower of Controlling Perception

Dr. Garner frames the ability to control our memories and expectations as a "superpower." By consciously shaping our thoughts and expectations, we can change how we experience the world. If we don't use this superpower, we will remain stuck in our existing patterns of perception. "When you change the way you look at things, the things you look at change." The choice of which internal model to use is ultimately ours.

Synthesis/Conclusion

The video provides a compelling overview of how our brains integrate sensation, thought, and expectation to create our perception of the world. Dr. Garner's research demonstrates the plasticity of memory and the importance of updating our internal models to adapt to a changing environment. By understanding these principles, we can consciously shape our experiences, improve our learning, and foster greater understanding and empathy in our interactions with others.